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- Title
Direct Modeling of the Mechanical Strain Influence on Coda Wave Interferometry.
- Authors
Azzola, J.; Schmittbuhl, J.; Zigone, D.; Magnenet, V.; Masson, F.
- Abstract
Abstract: Coda waves interferometry (CWI) aims at tracking small changes in solid materials like rocks where elastic waves are diffusing and so intensively sampling the medium, making the technique more sensitive than those relying on direct wave arrivals. Its application to ambient seismic noise correlation, referred to as ambient noise interferometry, has found a large range of applications over the past years like for reservoir monitoring or regional fault evolution. Physically, the changes in phases observed are typically interpreted as small variations of seismic velocities. However, this interpretation is questionable. The goal of the present work is to show from a direct numerical modeling that deformation signal also exists in CWI measurements which might provide new outcomes for the technique. For this purpose, we model seismic wave propagation within a diffusive medium using a spectral element approach (SPECFEM2D) during an elastic deformation of the medium. The mechanical behavior is obtained from a finite element approach (Code_Aster) keeping the mesh grid of the sample constant during the whole procedure to limit numerical artifacts. CWI of the late wave arrivals in the synthetic seismograms is performed using both a stretching technique in the time domain and a frequency cross‐correlation method. Both show that CWI is sensitive to the heterogeneity of the elastic deformation field in addition to the isotropic volumetric deformation and independently of nonlinear acoustoelastic effects. Implications for strain monitoring of reservoirs are discussed.
- Publication
Journal of Geophysical Research. Solid Earth, 2018, Vol 123, Issue 4, p3160
- ISSN
2169-9313
- Publication type
Article
- DOI
10.1002/2017JB015162